But there are of course a few details to settle. Like the one that Tory Shadow Chief Secretary Philip Hammond fell over on last night's Newsnight - what does it actually mean to say that taxes will fall as a share of GDP over an economic cycle?

Paxman had great fun with poor Mr Hammond. What is an economic cycle? Where are we in it now? Is the current tax take too high? How low should the percentage be?

Hammond wobbled around all over the road.

Well, the economy is sometimes above trend, and sometimes below...

Yes, but where is it now?

Well, I don't know... that's for the statisticians to tell us...

You don't know?

Well, ahhhhgh... Hammond's front wheel buckled and he ended in the ditch.

What Newsnight highlighted is that much more work needs to be done on this "sharing the proceeds" stuff. As we've blogged many times, it's still no more than a nifty slogan. With Hammond likely to be at HMT within two years, he needs to get some serious content.

We wonder if he has any idea what the job of Chief Secretary to the Treasury actually involves? Chiefy is the most hated member of the Cabinet. While his boss the Chancellor gets all the plaudits for cutting taxes, Chiefy is the one who has to deliver the public expenditure control that funds them. He's the one who has to say no to all his Cabinet colleagues as they attempt to grab more and more for their own departments.

Cameron's cabinet will be different, and they'll all commit to slashing departmental waste on their own turf?

Where on earth have you been these last 150 years? Even poor tortured low tax Keith Joseph found himself presenting a departmental brief arguing for more industrial subsidy cash in those bleak early years of Thatcher. It's the nature of the beast, and whatever their best intentions may have been, once spending ministers get their feet under their huge new desks, they get turned (Yes Minister, op cit).

Which is why we need clear upfront rules and quantified commitments. Hammond needs a big visible stick to beat off his colleagues. Discretion and Best Endeavours simply won't work.

It's time to beef up sharing the proceeds with that Third Fiscal Rule - a fixed and quantified target for cutting the share of public spending in GDP over a cycle, now with added endorsement by the OECD (see many previous blogs, eg here).

Come on Mr Cameron - you're so nearly en route to the Promised Land. Just one more heave. Or whatever it is you do to ride a bike.

PS The real answer to Pax's cycling questions is surely that the Treasury already publishes estimates of the cyclically adjusted fiscal deficit, and the Tories would merely be adding publication of the adjusted tax and expenditure numbers. Here's HMT's current chart from the Budget, showing we have been in cyclically adjusted deficit every year since 2002-03:

Of course, as we all know, the Treasury numbers are now so massively fiddled, they're not worth the paper they're printed on. But the methodologies used to make such adjustments are broadly understood and agreed. What's more, George Osborne has already pledged to establish an independent fiscal monitoring office to do the calcs (modelled on the NAO). So why didn't Mr Hammond say that? They need to be far more specific in their own thinking.

Are you sure you can ride that thing?

Hurrah! For the first time since 1472 the political cycle has turned. Tax and spend is out, and tax cuts are back on the centrist agenda.

But there are of course a few details to settle. Like the one that Tory Shadow Chief Secretary Philip Hammond fell over on last night's Newsnight - what does it actually mean to say that taxes will fall as a share of GDP over an economic cycle?

Paxman had great fun with poor Mr Hammond. What is an economic cycle? Where are we in it now? Is the current tax take too high? How low should the percentage be?

Hammond wobbled around all over the road.

Well, the economy is sometimes above trend, and sometimes below...

Yes, but where is it now?

Well, I don't know... that's for the statisticians to tell us...

You don't know?

Well, ahhhhgh... Hammond's front wheel buckled and he ended in the ditch.

What Newsnight highlighted is that much more work needs to be done on this "sharing the proceeds" stuff. As we've blogged many times, it's still no more than a nifty slogan. With Hammond likely to be at HMT within two years, he needs to get some serious content.

We wonder if he has any idea what the job of Chief Secretary to the Treasury actually involves? Chiefy is the most hated member of the Cabinet. While his boss the Chancellor gets all the plaudits for cutting taxes, Chiefy is the one who has to deliver the public expenditure control that funds them. He's the one who has to say no to all his Cabinet colleagues as they attempt to grab more and more for their own departments.

Cameron's cabinet will be different, and they'll all commit to slashing departmental waste on their own turf?

Where on earth have you been these last 150 years? Even poor tortured low tax Keith Joseph found himself presenting a departmental brief arguing for more industrial subsidy cash in those bleak early years of Thatcher. It's the nature of the beast, and whatever their best intentions may have been, once spending ministers get their feet under their huge new desks, they get turned (Yes Minister, op cit).

Which is why we need clear upfront rules and quantified commitments. Hammond needs a big visible stick to beat off his colleagues. Discretion and Best Endeavours simply won't work.

It's time to beef up sharing the proceeds with that Third Fiscal Rule - a fixed and quantified target for cutting the share of public spending in GDP over a cycle, now with added endorsement by the OECD (see many previous blogs, eg here).

Come on Mr Cameron - you're so nearly en route to the Promised Land. Just one more heave. Or whatever it is you do to ride a bike.

PS The real answer to Pax's cycling questions is surely that the Treasury already publishes estimates of the cyclically adjusted fiscal deficit, and the Tories would merely be adding publication of the adjusted tax and expenditure numbers. Here's HMT's current chart from the Budget, showing we have been in cyclically adjusted deficit every year since 2002-03:

Of course, as we all know, the Treasury numbers are now so massively fiddled, they're not worth the paper they're printed on. But the methodologies used to make such adjustments are broadly understood and agreed. What's more, George Osborne has already pledged to establish an independent fiscal monitoring office to do the calcs (modelled on the NAO). So why didn't Mr Hammond say that? They need to be far more specific in their own thinking.

Welcome to the TPA

Welcome to The TaxPayers' Alliance, Britain's grassroots campaigning group dedicated to reforming taxes, cutting spending and protecting taxpayers. If you like what we do, become a supporter now by signing up to our mailing list using the form below. John O'Connell, Chief Executive